Mark Mor When thru'put is increased by 40-50% (like 170 MMD to 250 MMD), a combined team of Process Engineer, Design Engineer, Inspection (Corrosion & Metallurgical Engineer), Operation (Chemical engineering background in operation) should first sit together whether the orignal design is adequate to take this excess flow or pressure or temperature or velocity increases . Its adequacty ( ie., capacity of plant equipment / piping / control systems) to take this excess thru'put load should first be evaluated from the points of : Additional flow / increase in velocity, temperature changes (if any) or pressure variations in : piping, control valves, pumps, exchangers, and then finally static vessels. Also a study if vessel has SRV (Safety Relief Valves)with adequate relief measures to take this excess capacity It is a combined role of a group of engineers in the plant. Trust this help you C.V.Srinivasan Nishi Engineers Pvt. Ltd India Aug 11,2006 E-mail:nish@vsnl.com >HI >If the rate at the crude unit increased from 170 MMD to 250 >MMD for assort time 20 days. What the corrosion engineer >involvement here what the management of change should be >done (MOC) > >thanks